1. Field of the Invention
This invention relates to a semiconductor integrated circuit device and more particularly to a semiconductor integrated circuit device having an electrically rewritable nonvolatile semiconductor memory device.
2. Description of the Related Art
In an electrically rewritable nonvolatile semiconductor memory device, for example, in a multi-level flash memory, the distribution width (Vthmin−Vthmax) of a write threshold voltage is large. Therefore, there occurs a problem that the data holding characteristic is bad in the write threshold voltage in a state in which the highest threshold voltage is set.
Reference Document: U.S. Pat. No. 6,643,188